Railway car truck spring



Oct. 17, 1933. T. H. sYMlNG-roN 1,930,530

RAILWAY CAR TRUCK SPRING Filed June 18, 1931 2 Sheets-Shee l RAILWAY CAR TRUCK SPRING Filed June 18, 1931 2 Sheets-Sheet 2 .-oa'd ip Zanon-nds of Hunnl N 'Il u o www natural period of vibration of the springs coinsuch that at different positions or decrease of 80 patented oci. 17, 1933 y 1,930,630

RAILWAY CAR TRUCK SPRING Thomas H. Symington, Baltimore, Md., assignor to T. H. Symington & Son, Inc., Baltimore, Md., a corporation of Maryland v Application June 18, 1931. Serial No. 545,336

11 Claims. (Cl. 267-4) The invention relates to railway car truck vertical jiggle would be checked. Of course such springs and has .special reference to that type would be a physical impossibility and it would located Within the window openings of the side therefore be necessary to adopt an arrangement frames for the purpose of yieldably supporting and construction wherein use is made of springs 5- the bolster and of course the load thereon. which will perform differently under diierent 60 The principal Object 0f the invention, gerlconditions so that the objectionable vibratory erally stated, is to provide a spring construction movement lwm be checked. and Combination based Upon the ideal spring It is with all of the above facts in view that I Curve Which is Calolilated to be gradual or comhave devised the present invention which conlo paratively iiat at the beginning of the travel and templates the provision of a truck spring assem- 65 to be increasingly abrupt along a series of SuC- bly based on the ideal curve, as mentioned hereoessve steps, the plurality 0f breaks in the direoinbefore, and which embodies a plurality of units, tion of the Curve Corresponding to and being certain oi?y which are effective under all loads and indicative of the spring, action under different others of which will come into play either when load conditions and at diierent points in the the load is increased or when certain of the 70 travel. units have been depressed to a certain predeter- Whenever a truck bolster is supported upon mined travel, it being an important feature that springs of any standard type, it has been found the various springs have different natural periods that there is always a certain tendency of the of vibration so that the working curve of the 29 Springs to vibrate vertically 0r jigg1e. When entire assembly will be stepped or broken at in- 75 this movement builds up the effect on the car, tervals. and its lading, particularly in the case of perish- Another. object of the invention is to provide ablelgoods, is most injurious. This vertical jig- `a spring'f'assembly having a stepped or broken 'gie develops to its maximum extent when the working curve and in which the arrangement is cides with the frequency of the jolts or impulses loading the spring will start to vibrate at the caused by passage of the car wheels over the natural critical speed of that portion of the curve rail joints. When this synchronization occurs, and will continue to vibrate until the movement which it is bound to do at certain critical car rides into the angular curve either above or below o0 speeds, the situation becomes really alarming, the particular loaded position, the theory being 85 thus necessitating that steps be taken to check that at this new portion of the curve there will it. When the speed is accelerated or decelerated be a diierent critical speed so that the eiect will so as to break up this synchronization the verbe to break up the car jiggle without any noticetical jiggle is checked but, unfortunately, in the able shocks within the car. case of long or solid trains the rate of accelera- A more specic object of the invention is to 9 tion or deceleration is comparatively slow so provide a truck spring assembly in which there that this destructive jiggle may continue for a is a soft spring resistance to light load gradually considerable length of time, for instance while increasing step by step by either a uniform or the trainis travelling a mile or even considerably vary'ng increment until a certain predetermined 40 more whichit must do before lthe speed will load limit is reached, after which theresistance 95 Change suielentir from tbe critical. speed t0 nr capacity is materiauy increased and maineffect any appreclafble checlmgtained substantially constant in successive steps. T he exactfbehavlor of sprmgs of dlfferent types Another important object is to provide a spring Vanes-a-nd 1" has been found by actfml ,test that assembly including a plurality of units certain of the Cntmal speed for an A' R A' Sprmg 1s thirty' which have different deflection rates at different 100 $221? eilsypeshctrngg erolkhf points in their travel, as discussed inmy co-pend- When-the load on such springs is plotted against mg apphcatml med Februfary 5th' 19311 Slelsa the travel the working curves of the two types No' 513690 a d au of Whlch are. ca ou a' e from a certain point below subtend an angle of about eighteen degrees coras to suppfrt me load 105 responding to a change in the critical speed of to a certain point above the critical train speed ve miles as mentioned ab0ve 1f while a car is in such manner -as positively to preclude the detravelling and reaches the critical speed it were VelODment 0f excessive Vertical jiggle the Combi' feasible to replace one type of springs with imnation further including certain initially snubbed other it is quite apparent that the tendency to `units which will give materially increased capac- 110 ity for sustaining the heaviest loads and additionally acting to prevent vertical vibration.

A further object of the invention is to provide a spring assembly having the above pointed out characteristics and in which the only change necessary in the equipment to accommodate the same is the replacement of the ordinary type of truck bolster by one permitting certain of the spring units to extend up thereinto.

Another object is to provide a spring assembly in which the number and arrangement of units, or the selection thereof, or the size of the stock from which they are formed, may be varied, depending upon the capacity of the car beneath which the assembly is to be used, it being obvious lthat greater capacity is needed for cars of the forty, fty-iive and seventy ton type than for those of thirty ton capacity, it being within the purview of the invention to resort to all conceivable modications requisite for the proper cushioning of cars of various capacities, provided there is no deviation from the underlying principle.

A further object is to provide a truck spring assembly in which the units are individual so that certain ones may be interchanged, an added ieature being to provide an assembly which will be simple and inexpensive to make and easy to install as well as eilicient and durable in service, and a general improvement in the art.

To the attainment of the foregoing and other objects and advantages, the invention preferably consists in the details of construction and the arrangement and combination of parts to be hereinafter more fully described and claimed, and illustrated in the accompanying drawings in which:

Figure 1 is a fragmentary elevation, with parts broken away and in section, of a truck side frame having mounted therein a spring assembly constructed in accordance with my invention and supporting the bolster, the bolster being in section and the spring assembly being likewise partially in section on the line 1-1 of Figure 3.

Figure 2 is a vertical sectional view taken on the line 2-2 of Figure 1,

Figure 3 is a diagrammatic plan view with the bolster indicated by dot and dash lines, and

Figure 4 is a diagram 'showing the working curve of my spring assembly in comparison with the working curves of springs of different types.

Referring more particularly to the drawings, I have shown, generally, a portion of a side frame including the usual compression and tension members l0 and 1l connected by column vguides ,i2 dening a window opening 13 for the reception of the bolster 14 supported upon the spring assembly to be described which in turn rests upon the spring seat 15 at the bottom of the window opening. The bolster may be of any ordinary or preferred construction except 'that the end portion is formed with a longitudinally extending recess. 16 for the reception of certain oi' the spring units to be described. in other respects the bolster may be standard and it is also *contemplated thatthe distance between the bottom surface thereof and the seat l5 accord with thev standard or accepted practice.

in carrying out my invention l provide a spring assembly comprising a plurality of units of different characteristics in so far as height, capacity, size and travel are concerned so as to bring about the desired stepped or broken working curve. This assembly. in the present instance is shown as comprising a pair of` similar units designated as a Whole by the numeral 17 and each including assenso outer and inner coils 18 and 19 of varying pitch, the convolutions of maximum pitch being located at the center and those of the decreased pitch being divided, preferably equally between the two ends, this being resorted to because of the fact that as they have less pitch than the center coils they are under a correspondingly less strain or have a correspondingly less stress and may go solid without danger of breaking at the ends. While dimensions are not to be considered restrictive it is preferable that the outercoils 18 be of 14 and 33g inches free height and approximately 11 and 'M3 inches solid height and' it is on account of this considerable height that the recess 16 is provided in the underside of the bolster to accommodate these units. The inner coils 19 are held under a certain initial compression or snubbed by means of bolts 20 which extend axially through the units and which have enlarged heads 2l overlying and constitutingabutments for the upper ends of the coils 19. -At the bottom of each of these units 17 is an individual spring cap 22 centrally apertured for the passage of the snub bolt 20 which maintains its snubbing relation by virtue of a nut 23 which abuts against the underside of the cap 22. The seat 15 at the bottom ofv the window opening is necessarily formed with openings 24 accommodating the nuts 23 as will be readily apparent from an-inspection of the drawings. A feature of importance is that each snub bolt 20 is provided beneath its .head 21 with an enlarged shank 25 tting comparatively closely within the upper end of the inner coil 19 and is also provided at a point spaced somewhat above the individual cap 22 with an enlargement 26, the enlargements 25 and 26 iittingr comparatively closely within the inner coil 19 and serving to center the same. The outer coil 18 of each unit may be considered as centered by its engagement about the inner coil so that relative lateral displacement in any direction will be prevented. The inner coils l9` being snubbed` down or held under compression by the bolts 20 have their upper ends below the upper ends of the outer coils 18 and therefore do not come into play until the coils, 18 have been depressed to a certain predetermined extent.

I also make use of other units, a pair being shown in the present instance, indicated generally by the numeral 27 arranged between the spring seat and the underside of the bolster. Each of these units includes an outer coil 28 of substantially standard 'height and having convolutions preferably of uniform pitch. Within each coil 28 is an inner 'coil 29 of considerably less free height upon which is mounted a follower 30 here disclosed as of cup-like form and containing a coil spring 31 bearing against the underside of the bolster. Each unit 27 may be described as a triple unit inasmuch as in addition to the springs 28, 29 andf31 it includes an innermost spring 32 located within the confines of the spring 29 and held under a certain predetermined degreeof initial compression, or snubbed down, by an axially extending bolt 33. Each bolt has its upper end formed with a head 34 overlying the upper end of lthe spring 32 and snubbing is effected by means of a nut 35. Each of. the units 27 has its individual bottom cap' 36 centrally apertured for the passage of the bolt 33, the nut 35 engaging against the underside of the disk-like cap. The spring seat 15 is formed with openings 37 for the reception of these nuts; The bolts 33 are similar in connection to the bolts 20 inasmuch as they are formed beneath their heads `17 are snubbed by means of the bolts 21.

and at their lower portions with enlargements 38 and 39 which t fairly closely within the springs 32 and which operate to effect centering thereof `and to prevent relative displacement laterally of all the coils in each of the units. Clearly the engagement of the nuts 23 and 35 Within the openings 24 and 37, respectively, will hold all of the units in the nest in proper position.

Assuming that the nest has been constructed and disposed in the side frame in the proper relation to the bolster as shown and described, it will be seen that the initial load comes upon the outer coils 18 of the units 17 and also upon the outer coils 28 of the units 27. It has been above mentioned that the innerprings 19 of the units It should, however, be noted that they are not both snubbed down, preferably, to the same extent, the one at the right of Figure 2 being shown as snubbed down to a greater extent than the one at the left in the same gure. Actually the inner spring 19 of the unit 17 at the right of Figure 2 is preferably snubbed down so that its normal height will be one inch below the top of the outer coil 18 whereas the inner coil 19 in the unit 17 at the left oi the same g'ure is snubbed down only tof an inch. The effect of this isA that when the outer coils 18 and 28 are deflected by an increase in the load or as the result of vertical jiggle so that the bolster moves downwardly of an inch the inner coil 19 of the unit 17 at the left of Figure 2 becomes energized. When the springs 18, 28 and the inner spring 19 of the left unit 17, considering Figure 2, are additionally compressed by downward movement of the bolster an additional T36 of an inch the inner coil 19 of the unit 17 at the right of Figure 2 becomes energized.' When the bolster moves downwardly 1 and inches the underside thereof will 'en gage against the heads 34 ofthe bolts 33 and energize the innermost springs 32 of the units 27. When the downward movement is increased an additional inches the underside of the bolster Will engage against the rollowers 13 so that the load will come upon and be yieldingly supported by the intermediate springs 29 of the triple spring units.

The result of the foregoing action is that there `will be a series of distinct breaks or steps in the` working curve shown in Figure 4. In this graph it will be observed that I have illustrated the performance curve of a spring nest of the Norfolk and Western type, the Dalmantype and the A. R. A., all indicated respectively by the numerals 38, 39 and 40, in comparison with the working curve 41 of the present assembly. While again actual figures are not to be construed as restrictive or limitative, I have for the sake of illustration shown a break in the working curve 41 at a load of 21,500 pounds and a travel of 41% inches, this being the point where the innermost coil 19 of the snubbed unit 17 at the left of Figure 2 comes into play; a second break at asload of 28,600 pounds and at a travel of one inch, this being the point at which the inner coil 19 of the other unit 17 becomes energized; a thirdbreak at a rate of 35,900 pounds and a travel of 1 and Sg inches, this being the point where the snubbed inner springs 32 of the triple coil units become energized; andan additional break or step at a load 4of 44,000 pounds and a travel of 1 and inches, this being the point where the bolster engages the followers 30 for energizing the springs 29.

Owing to the fact that the increased height springs 18 and 19 are formed of coils of different pitches, it is clear that such coils will have varying natural periods of vibration so that there will be little danger of building up any vertical jiggle. Furthermore the travel is comparatively slight, only inches, before a snubbing action occurs. Any tendency of the then energized springs to build up a jiggle vwill be effectually Ichecked at another` inch travel. All of the springs up to this point with the exception of the springs 28 are of varying pitch so that the f-ull benets of the diierences in natural periods of vibration will be obtained. Additional jiggle developing tendencies beyond the point last mentioned Will be eiectually checked when the springs 32 and 29 come successively into play. The differences between the loads or travels at-which the various snubbing actions take place are comparatively slight so that even though there should be a slow acceleration or deceleration rate in a train jiggle at any frequency will not continue for any prolonged time. In this way damage to the car parts and particularly to the lading will be avoided.

The equipment described and shown is intended primarily for use under box `cars of fifty-five ton capacity. In the event the spring nest is used for example under a fty-ve ton coal car where the load is always at maximum capacity instead of variable, the number of snubs or steps or breaks in the Working curve may be reduced. When the spring assembly is to be used in a forty ton car it may simply be necessary to change the size of the stock from which certain of the units are made, and in caseof a thirty ton car a further reduction might be effected. The number of dead-end coils in the variable pitch springs may be varied if necessary so as to maintain the proper travel. For use in seventy ton cars it might be` necessary to provide additional springs k.of standard height similar to the springs 29 located beneath the bolster for providing increased capacity. Other variations might be resorted to without involving any change in the underlying principles.

From the foregoing description and a study of the drawings it is believed that the construction, operation and advantages should be readily apparent to one skilled in the art without further explanation. u

While I have shown a preferred embodiment of the invention and have described possible changes it should be understood that the disclosure is merely an exemplication of the principles involved and that the right is reserved to` make all such variations and modications in the construction, the exact combination, the times at which the different elements come into'play, as regards-load and travel, as will not depart from the spirit or the scope of the claims hereunto appended.

Having thus described theinvention, I claim:

1.- In a-railway car truck, a side frame having located Within the Window opening, said assem- 1 bly including a plurality of springs engaging within said recessand always under compression..

other springslocated within said first named springs and held under initial compression to be of less height and to become energized subsequent to the energization of the first named springs, and additional springs bearing against the unat the same level.

2n In a railway car truck, a side frame having a window opening therein, a bolster having its end extending into the window opening, and provided with abutments at diiierent levels, and a supporting spring assembly located within the window opening, said assembly including a plurality of springs engaging against certain of said abutments and always under compression, other springs located within said rst named springs and held under initial compression so as to be of less height than the same and to become energized subsequent to the energization of the nrst named springs, and additional springs bearing against the remaining abutments and enclosing absorption means, all of said springs seating at the same level.

3. In a railway car truck. a side frame having a winddw opening therein providing a single level seat, a bolster having its end extending into the widow opening, the bolster having its end formed with an upwardly extending recess, and a supporting spring assembly located within the window opening, said assembly including a plurality of springs of greater height than the distance between 'the seat and bolster engaging within said recess and maintained always under compression, other springs of the same free height located within said irst named springs and held under initial compression so as to be of less effective height and to become energized subsequent to the energization of the iirst named springs, and additional springs of less free height than the first springs bearing against the underside of the bolster and enclosing still other springs held under initial compression, all of said springs resting on said single level seat.

e. In a railway car truck, a side frame having a window opening therein, a bolster having its end extending into the window opening, the bolster having its end formed with an upwardly extending recess, and a supporting spring assembly located Within the window opening, said assembly including a plurality of springs engaging Within said recess and always under compression, other springs located within said rst named springs and held under initial compression to be of less height and to become energized subsequent to the energization of the first named springs, additional springs bearing against the underside or" the bolster and enclosing still other springs held under initial compression, and a :further set of springs of still lower height interposed between said last named springs and the third named springs.

5. ln a railway car truck, a side :trarne having a Window opening therein, a bolster having its end extending into the window opening, the bolster having its end formed with an upwardly extending recess, and a supporting spring assembly located within the window opening, said assembly including a plurality of springs having their upper ends seated within said recess, snubbed or less height located within said springs; and additional units engaging against the underside oi the bolster, said additional units comprising a combination of free and snubbed springs oi progressively varying heights.

o. in a railway car truck, a side frame having a window opening therein, a bolster having its end. extending into lthe window opening, the bolster having its end formed with an upwardly extending recess, and a supporting spring assembly located within the Window opening, said assemderside of the bolster, all of said springs .seatingv bly comprising a unit including free and snubbed springs engaging within the recess, and a unit including a plurality of axially arranged springs engaging against the underside of the bolster, the springs in the second named unit being of varying heights lto be successively energized and certain thereof being free and certain being snubbed.

7. A spring assembly for supporting a bolster within a side frame, comprising a plurality of units extending up into a recess in the underside of the bolster, each unit including an outer spring having convolutions of diierent pitches and an inner spring held under initial compression, and a plurality of units engaging against the underside oi the bolster, each of said second named units comprising a snubbed spring surrounded by an additional spring of less free height.

8. In a railway car truck, a side frame having a window opening therein, a bolster having its end extending into the Window opening, the bolster having its end formed with an upwardly extending recess, and a supporting spring assembly 1oca'ted within the window opening, said assembly comprising a plurality of units located Within the recess and each including an outer coil and an inner coil both having convolutions of different pitches andl the inner coil being snubbed, and a plurality of units engaging against the underside of the bolster, each of said second named units comprising an outer coil, an inner coil snubbed down to have less free height than the outer coil and a normally free coil of less free height than the inner coil. L

9. A spring assembly for supporting a bolster in a side frame, the bolster being formed in its underside withl a recess, comprising a unit located within the Window opening and said recess and including outer and inner coils, bolt means extending axially through the inner coil for maintaining the same under initial compression, means on said bolt means for centering the inner coil withj/respect thereto, and other springs engaging against the underside of the bolster, the side frame being provided at the bottom of the window opening with openings permitting the passage of said bolt means.

l0. A spring assembly for supporting a bolster in a side frame, the bolster being formed in its underside with a recess, comprising a unit located Within the Window opening and said recess and including outer and inner coils, bolt means extending axially through the inner coil for maintaining the same under initial compression, means on said bolt means .for centering the inner coil with respect thereto, and other springs engaging against the underside of the bolster, the side frame being provided at the bottom of the window opening with openings permitting the passage of said bolt means, the last named springs comprising the combination of a plurality of concentric coils arranged to become successively energized.

ll. A spring assembly for supporting a bolster Within a Window opening, comprising a spring unit including outer and inner coils, the bolster being provided at its underside with@J recess and said outer coil having its upper end engaging against the top wall of the recess, a bolt extending through the inner coil for maintaining the same under initial compression, means on the boit for centering the inner coil with respect thereto, and the side frame being provided with an opening :for the passage of the bolt.

THOMAS H. SYMINGTON. 

